N = 128;
N2 = N/2;
len = 16

[lp,hp] = frespondSingle(N,len);

plot(abs(lp(N2:end)))
hold on
plot(abs(hp(N2:end)),'-g')

N = 128;
N2 = N/2;
len = 1

[lp,hp] = frespondSingle(N,len);

plot(abs(lp(N2:end)),'.-r')
plot(abs(hp(N2:end)),'.-y')